After traversing through the database server on the search for tables without primary key I found “log_profiling”.
This was addressed in issue #287. That was not a problem for us yet. But we’re thinking about making the database a little bit HA (and load balanced via MySQL-Router) by using the new replication groups feature. But under Requirements and Limitations it is stated, that every table must have a primary (not only a unique key as in Mysql.php source, s. line 211. So please try to resolve this to get compatible to the newest HA feature of MySQL.